Foot operated speed control units and systems for air driven dental handpieces



Sept. 18, 1962 M. STAUNT 3,054,137

FOOT OPERATED SPEED CONTROL UNITS AND SYSTEMS FOR AIR DRIVEN DENTALHANDPIECES Filed April 11, 1960 7 Sheets-Sheet 1 M. STAU NT 3,054,187

TS AND SYSTEMS HANDPIECES Sept. 18, 1962 FOOT OPERATED SPEED CONTROL UNFOR AIR DRIVEN DENTAL 7 Sheets-Sheet 2 Filed April 11, 1960 95/ an m bmm NMWN WSW

Sept. 18, 1962 M. STAUNT FOOT OPERATED SPEED CONTROL UNITS AND SYSTEMSFOR AIR DRIVEN DENTAL HANDPIECES 7 Sheets-Sheet 3 Filed April 11, 1960fwuw L36 8% INVENTOR. 5/02/776 Qyf j/zmf "fiorvg Sept. 18, 1962 M.'STAUNT 3,054,187

FOOT OPERATED SPEED CONTROL UNITS AND SYSTEMS FOR AIR DRIVEN DENTALHANDPIECES Filed April 11, 1960 7 Sheets-Sheet 4 RD. Q 7

DRIVE-.

IN V EN TOR.

Sept. 18, 1962 M. STAUNT 3,054,187

FOOT OPERATED SPEED CONTROL UNITS AND SYSTEMS FOR AIR DRIVEN DENTALHANDPIECES '7 Sheets-Sheet 5 Filed April 11, 1960 .lLllal llllrlln Sept.18, 1962 M. STAUNT ERATED SPE OR AIR DR 3,054,187 ED CONTROL UNITS ANDSYSTEMS IVEN DENTAL HANDPIECES FOOT OP '7 Sheets-Sheet 6 Filed April 11,1960 6 l l l I l I l l I l l l I l i l l I I l a I I I I I I l RA mm M vW 5 Q a a i g: F. N% g v N A. mfllmqhbml Hlfih 3 w w l l wM hm xi N: I.H N\ g m NQ\ om R,

Sept. 18, 1962 M. STAUNT 3,054,187

FOOT OPERATED SPEED CONTROL UNITS AND SYSTEMS FOR AIR DRIVEN DENTALHANDPIECES 7 Sheets-Sheet 7 Filed ,April 11, 1960 IN VEN TOR. W yM /M@%ttes 3 054 187 FOOT OPERATED SPI IED CONTROL UNITS AND SYSTEMS FOR AmDRIVEN DENTAL HAND- The present invention relates to foot operated speedcontrol units and systems for air driven dental handpieces, and isparticularly concerned with the provision of an improved foot operatedair valve and electric switching arrangement for use with air drivendental handpieces. One of the objects of the invention is the provisionof an improved foot operated speed control unit for air driven dentalhandpieces which permits the user to turn on the air drive for thehandpieces and to regulate the speed from zero to maximum up to 250,000rpm. and to simultaneously turn on the flow of cooling water which isentrained with the air spray directed on all sides of the dental burinto the cavity and also enabling the user to turn oif the air drive andwater with his foot and to turn on the flow of chip cleaning air intothe cavity without removing the handpiece from the mouth, but onlymoving the handpiece until the bur is out of the cavity and the chip airis directed into the cavity.

Another object of the invention is the provision of an improved footactuated speed controlling unit of the class described which graduallyvaries the speed from zero to maximum, and which can also be used to cutoff the drive air and water and turn on the chip air by another movementof the foot.

Another object of the invention is the provision of an improved speedcontrol unit for air driven dental handpieces which promotes greatersafety in its operation, since it is impossible to start the handpiececontrol by this unit at high speed, which might result in injury to thepatient; and it is necessary always to begin at low speed, and speed upgradually after the tool has been properly located adjacent the tooth.

Another object of the invention is the provision of an improved footcontroller for air driven dental handpieces which is so constructed thatthe dentist is not required to shift his weight, but the foot controllermay be operated by the dentist by rotating his foot upward or downwardon the heel of the foot, causing his toe to operate upon the cammingsurface of the foot controller pedal to control the speed of operationof the handpiece.

Another object of this invention is the promotion of safety for thepatient and the dentist and a reduction of fatigue on the part of boththe patient and the dentist, and the reduction of time required for thepreparation of cavities, and the promotion of steadiness on the part ofthe dentist in manipulating the cutting instrument when operating athigh speeds.

Another object of the invention is the reduction of ball bearing wear,and increasing the useful life of the ball bearings of the air drivendental handpiece, since the ball bearings are more likely to skidinstead of rotating, due to inertia, when started at high speed; andwhen the handpiece is started slowly from zero speed, the ball bearingsare less likely to skid, thus reducing excessive wear on the ballbearings.

Another object of the invention is to permit the dentist to changequickly from drilling to chip blast and back to drilling and to promotemaximum visibility and higher accuracy in the preparation of cavities ina minimum amount of time, since the dentist need not change hisposition; and he need not hang up the contra angle on the supportinghook while picking up an air syringe to clean out the cavity, whichpermits the patient to change his position, and requires readjustmentwhen the handpiece is again to be applied to the tooth with the methodsof the prior art.

Another object of the invention is to permit the dentist to changequickly from drilling to chip blast and back to drilling, as a singleand continuous operative procedure, instead of interrupting theoperation, to hang the handpiece up and reach for an air syringe, as wasdone in the methods of the prior art; thus maximum visibility, greateraccuracy in the preparation of cavities and reduction of total time areachieved, since the dentist need not change his position and the patientlikewise cannot change position, eliminating the former necessity forreadjustment with respect to the changed position of the patient uponreentering the mouth to continue the restorative procedure.

Another object of the invention is the provision of tooth drillingequipment which may be operated at the ultra high speeds and power thatare required for cutting tooth enamel, but which is also adapted to beoperated at even slower speeds with less power, such as are desirablefor the removal of various material and for finished cutting in thedentine of the teeth.

Another object is the provision of an improved foot actuated controllerwhich is so arranged that the switch is operated prior to the opening ofthe air drive valve so that the control cabinet manifold pressure isfirst relieved, preventing an initial surge of air at starting whichwould cause the bur to rotate unexpectedly.

Another object is the provision of an improved foot actuated controllerwhich is so arranged that a normally closed contact in the electricswitch, opens the chip air solenoid, in the control cabinet,simultaneously with the closing of the drive air solenoid, upon releaseof the foot pedal, so as to bleed off all air pressure in the cabinetmanifold and connecting line; this prevents an initial surge of air atstarting of the handpiece that could cause the bur to rotateunexpectedly.

Other objects and advantages of the invention will be apparent from thefollowing description and the accompanying drawings, in which similarcharacters of reference indicate similar parts throughout the severalviews.

Referring to the seven sheets of drawings accompanying thisspecification,

FIG. 1 is a view in perspective showing my foot operated controller foran air driven dental handpiece mounted adjacent a standard footcontroller for engine driven handpieces;

FIG. 2 is a bottom plan view of the supporting bracket for the footoperated controller;

FIG. 3 is a top plan view of the mounting brackets;

FIG. 4 is a sectional view taken on the plane of the line 4-4 of FIG. 3,looking in the direction of the arrows;

FIG. 5 is a fragmentary sectional view on a larger scale taken on theplane of the line 5-5 of FIG. 3, looking in the direction of the arrows;

' FIG. 6 is a top plan view of the controller;

FIG. 7 is a side elevational view of the controller;

FIG. 8 is a vertical sectional view taken on the plane of the line S-8of FIG. 6, looking in the direction of the arrows;

FIG. 9 is a vertical sectional View taken on the plane of the line 99 ofFIG. 6, looking in the direction of the arrows;

. FIG. 10 is a horizontal sectional view taken on the plane 10-10 ofFIG. 7, looking in the direction of the arrows;

FIG. 10A is a fragmentary enlargement of part of FIG. l

FIG. 11 is a wiring diagram;

FIG. 12 is a side elevational view of an air driven dental handpiece ofthe type controlled by my foot operated controller;

FIG. 13 is an end elevational view taken from the left of FIG. 12 on anenlarged scale;

FIG. 14 is a fragmentary top plan view of the handpiece head of FIG. 13;

FIG. 15 is a fragmentary bottom plan view of the handpiece head;

FIG. 16 is an elevational view of the air turbine unit;

FIG. 17 is a vertical sectional view taken through the hand piece ofFIG. 12 on the plane of the line 1717 of FIG. 14;

FIG. 18 is a similar sectional view extending from the right end of FIG.17;

FIG. 19 is a view in perspective of the air and water supply unit;

FIG. 20 is a diagrammatic view of the air and water supply unit,including the conduits and locating the elements of FIG. 19;

FIG. 21 is a top plan view of the controller casting, showing thevarious conduits therein.

Referring to FIG. 1, 150 indicates a standard foot controller for adental engine of the electric motor type driven by means of belts andpulleys. 151 indicates the cable containing the electric conductorsleading to the motor; and 152 indicates the control lever, which has twopedals 153 and 154 extending from the opposite sides of the electriccontroller 150.

In order to locate the present foot actuated controller for air drivenhandpieces in a convenient position, this air drive controller 165 iscarried by a circular base 156 at one side of the arm 157 between thenormal positions of the pedals 153, 154 and out of the range of movementof those pedals.

The base 156 has a laterally extending arm 157, which may berectangular, and which is provided at its right end with an upwardlypressed rectangular formation 158 having a central aperture 159 locatedin a circular depressed area 160.

The aperture 159 is adapted to receive a single screw bolt, the head ofwhich is recessed in a soft rubber layer of foam rubber 161, which isadhesively secured to the bottom of the bracket, and which has arectangular aperture 162 and a circular aperture.

The top of the pressed formation 158 is also covered with a soft foamrubber pad 164, both these pads being adhesively attached to thebracket.

By means of the single screw bolt extending through the aperture 159 andthreaded into the foot operated controller 165 the controller may beclamped in any desired rotative position relative to the electriccontroller 150.

The supporting base 156 has three sheet metal guide straps 166, 167, and168 pressed out of its body sufficiently, as shown in FIG. 5, to providea horizontally open slot for passing the adjustable radial clampingmembers 169, 170, and 171, each of which has a sliding body 172 provided with an end slot 178a for receiving a screw bolt 174, which hasits head spaced from the floor by the lower rubber pad 161; and thescrew bolts 174 are threaded into the straps 1664168 for clamping thesliding members 169- 171 in any adjusted position.

The base. 156 is also cut away to receive the body of each clampingmember 169-171 between the edges 175 of radial slots extending into thebase 156 at each clamping member 169. Each clamping member is upwardlyoifset at 176 so that it may extend over a portion 177 of the base andthrough the slot beneath the straps 166-168, where the clamping membersare secured by the screw bolts 174.

Each clamping member 169171 has an upwardly and inwardly curved flange,which is adapted to grip the projecting annular edge 179 of the enginecontroller 150.

These flanges 178 (FIG. 4) are preferably dipped in 4 rubber to preventmarring of the edge 179, which is clamped by them.

One of the clamping members, such as member 171, is provided with anauxiliary U shaped member 180 having the ends of its legs welded to theclamping member 171 and also dipped in rubber, forming an insulatedopening 131 for receiving and holding the hoses 182, 183 and electricalconductor 184 extending from the unit Referring to FIGS. 6 and 7, theseare top plan and side elevational views of the foot controller unit 165,which preferably comprises a cast metal body 200 which is generallyrectangular in shape, having a flat top 201 and rectangular sides 202,203, 204 with an inwardly extending rectangular slot 205 in the frontside 206.

The walls of the slot 205 are formed by a pair of forwardly projectinglugs 207, 208, which may have aligned through bores 209 for receiving apivot pin 210, which may be secured in place by an elongated set screw211 having a slot which is accessible from the bottom 212, the set screwbeing threaded into a threaded bore 213 and extending into engagementwith the pivot pin 210. The set screw preferably extends into an annulargroove 217 in the pin 210.

The side wall 204 is provided with a pair of integral diagonallyextending lugs 214, each of which has a threaded bore 2.15, 216 forreceiving the hose fittings 218 for attachment of the hoses 182, 183.

The pivot pin 210 serves as a pivotal mounting for a foot lever 219,which is preferably of angular shape, having an upwardly extendingflange or arm 220 and a forwardly extending arm or flange 221. Boththese arms are relatively wide, being as wide as the width of the slot205 in the body 201.

The lower corner 222 of the foot lever 219 is provided with a slotextending to the dotted line 223, leaving a pair of downwardly lugs 224supporting another pivot pin 225, upon which a metal roller 226 ismounted.

The body 201 supports a water ejector assembly of the type shown in FIG.9, which is the subject of a separate application, Ser. No. 857,010,filed December 3, 1959, now Patent No. 3,007,544, for Combined Filt rsand Water Ejectors for Air Lines; and this water ejector is mounted in athreaded bore 227, which is closed by screw plug 228'.

The water ejector is for the purpose of filtering the air and separatingit from the water of condensation which may have condensed in the linesleading to the foot controller, as such water tends to be mixed with theoil used, which is edible and water soluble; and such water tends alsoto swell the ball bearing retainers; and the water must, therefore, beeliminated.

The water ejector is mounted in the circular bore 229, whichcommunicates with an air inlet 230 and with a smaller counterbore 231having a gasket 232 against which a rigid porous filter sleeve 233 isseated and held by a metal sleeve 234 carried by screw plug 227.

The filter 233 passes water which collects in the space 235 at the endof counterbore 231 and is adapted to be discharged through the bore 236in a threaded fitting 237, which is threaded into the bore 238.

The threaded fitting 237 engages a gasket 239 by means of an annularflange effecting a water-tight seal at this point; and the fitting 237has a central aperture 241 against which a conical surface 242 on apiston rod 243 engages.

The piston rod has a cylindrical surface at 244 and a second cylindricalsurface at 245 separated by a groove 246, which has frusto-conicalwalls.

The fitting 237 has an internal groove 247 receiving an O ring 248adapted to effect a liquid-tight seal against either cylindrical surface244 or 245, but passes water when the O ring 248 is in registry with thegroove 246. Thus the aperture 241 is sealed off by the 0 ring 248, butis open to the discharge of water whenever the groove 246 passes the Oring by movement of the piston rod 243.

At its upper end the piston rod 243 supports a piston 249, which mayhave a reduced portion 250 of the rod pressed into a bore 251. Thepiston has a predetermined clearance at 252 in the cylindrical bore 253,passing some air at all times; and the piston has a cylindrical skirt254 with grooves 255 and through apertures 256, passing air to the holes257 and annular space 258 when the piston bottom surface rises above thelower edge of the internal groove in cap 228. Sleeve 234 carries an Oring 234a in a groove to seal the lower end of the sleeve 234.

The operation of the water ejector is as follows: When the air is turnedon, entering the inlet fitting 218 in the threaded bore 216, the airpressure lifts the piston 249 and momentarily the groove 246 passesthrough the O ring 248; and the air pressure ejects condensed waterthrough the aperture 241. Piston 249 passes to an upper position inwhich the aperture 241 is closed by an O ring engaging cylindricalsurface 245; and further ejection of the water is prevented and passageof air is prevented at the opening 241 until the air pressure is shutoff, when piston 249 again passes downward to the position of FIG. 9,again ejecting condensed water from the aperture 241 during this motion.

The outlet from the water ejector bore 229 is by way of a bored conduit259 to a bore 260 at the rear end of the metering valve 261, which isalso in communication with a bore 262 at the bottom end of the chip airvalve 263. Dry and filtered air is controlled by either of these valves,the outlets from which are in communication with each other through thecross conduit 264 and the outlet conduit 265 leading to the outlet port215.

The metering valve 261 comprises a cylindrical memher having its outerend 266 in position to be engaged by the roller 226 on the foot lever219; and the metering valve 261 is slidably mounted in a cylindricalbore 267 in a screw plug 268, which has its outer threads 269 threadedinto a threaded bore 270 in the body 200.

Bores 271 in the end of the plug are for receiving a spanner wrench; andthe annular flange 272 about the metering valve has a tapered groove 273for receiving a seal ring 274, which engages the cylindrical body 275 ofthe metering valve, establishing a dust-tight seal at the point ofengagement. An 0 ring 274a is carried in a groove in plunger 275,eflecting an air-tight seal with bore 322.

The screw plug 268 has a reduced cylindricalbody 276 extending intocounterbore 277; and a gasket 278 is clamped between the end of plug 268and the annular surface 279 to establish an air-tight seal at thispoint.

The screw plug 268 has a plurality of through bores 280 extendingthrough its reduced portion 276 to the bore 267; and the screw plug 268carries an enlarged cylindrical end portion 281, which has aperipherally extending groove 282 supporting an 0 ring 283, whichestablishes a seal in the counterbore 277. Thus the air space 284 issealed at both ends.

At its inner end the metering valve 261 has a cylindrical concentric lug285 and a seating surface 286 for receiving a compression coil spring287, the other end of which is seated in the complementary counterbore288; and the spring 287 urges the metering valve 261 toward the positionof FIG. 8.

The annular edge 289 in the plug enlargement 281 at the end of bore 267acts as a valve seat for engaging an O ring 290 contained in a groove291, which extends about the metering valve 261 at the left side of anannular flange 292.

When the parts are in the position of FIG. 8, the valve is closed at290, 289; but when the metering valve 261 is pushed inward toward theright, the valve is opened at 289, 290; and the metering valve 261 has aflattened portion 293 which establishes a gradually increasing openingbetween the flat 293 and the edge 289, gradually increasing the air flowfrom zero to maximum as the metering valve 261 moves inward toward theright in FIG. 8. Thus the metering valve 261 is adapted to control the 6flow of driving air from zero to maximum by means of pressure on thehorizontal portion 221 of pedal 219.

The user may turn on the drive air, causing the air driven handpiece tostart from zero air and zero speed; and the speed may be variedgradually up to maximum or held at any desired speed by holding the footpedal 219 at any desired position.

The foot pedal 219 is preferably actuated by pivoting the foot on theheel or the ball of the foot; and the flow of air is automaticallystopped by lifting or removing the toe from the lever 219, the spring287 closing the metering valve 261.

The chip air valve 263 comprises a cylindrical metal member having itsouter cylindrical surface 294 slidably engaged in a bore 295 in a secondscrew plug 296. The screw plug 296 has an enlarged threaded portion 297threaded into a threaded bore 298 in the body 200; and the enlargedthreaded portion 297 engages a gasket 299 seated at 300 in the threadedbore 298, eflecting an air seal at this point.

The screw plug 296 has a reduced cylindrical body 301 which slides intoa smaller counterbore 302 and is provided with a groove 303 carrying arubber O ring 304, effecting a seal at this end of the body 301. Betweenthe 0 ring 304 and gasket 300 the reduced body 301 has an annular groove305, which is in communication with the cross port 264 and with theoutlet 215.

There is another annular groove 306 on the inside of the bore 295 and aplurality of through apertures 307 joining the grooves 305 and 306.

The edge of the reduced plug 301 at the end of bore 295 is indicated at308 and serves as a valve seat to be engaged by an 0 ring 309 which isseated in a groove 310 above an annular flange 311 on the end of thechip air valve 263.

The chip air valve 263 also has a flattened portion 312, establishing aconduit from a point inside the 0 ring 308 to the groove 306, so thatwhen the chip air valve is opened at 310 and 308, air may flow from thebore 262 backward along the chip air valve 263 at the flattened portion312 to the groove 306, apertures 307, groove 305, and cross port 264,which is in communication with the outlet 215.

The chip air valve 263 also has an annular groove 313 containing arubber O ring 314, effecting a seal between the valve member 263 and theupper end of the bore 295. At its upper end the valve member 263 mayhave a tapered portion 315 receivable in a tapered bore 316 in a footactuated disc 317, which is secured on the plunger 263 by a flush headscrew bolt 318 threaded into a threaded bore 319 in the valve plunger263.

A coil spring 320 has one end located in an annular groove 321 on thelower side of the disc B17 and engages the body 298 with its other end,urging the chip air valve 263 into the closed position.

The volume and pressure of the chip air is controlled at the controlunit for the air driven handpiece; and the chip air valve 263 is usedfor turning on the chip air with the foot on the disc 317 whenever theuser wishes to clean out a cavity; and for this purpose he must removehis foot from the air control pedal 219, so that the handpiece is alwaysstopped when cleaning chip air is used.

Referring to FIG. 10, this is a sectional view taken through the body200 on a horizontal plane, showing the location of the air valve plunger261 inside the slot 205 adjacent the electrical plunger 321 forcontrolling the electrical circuits by means of which the solenoidvalves are actuated for controlling the flow of drive air, chip air, andwater.

The body 200 has a cylindrical bore 322 for slidably receiving theelectrical plunger, the end 323 of which projects farther than the airplunger 261 so that the electrical plunger is adapted to be actuatedfirst, prior to the initial opening of the metering valve. This actionso- 7 quence provides for the unloading of the control cabinet manifoldpressure and prevents an initial surge of air at starting, which wouldcause the handpiece bur tube to rotate unexpectedly.

The electrical plunger 321 has a reduced portion 324 between twocylindrical portions 325 and 326; and there are frusto-conical portions327 and 328 at each end of the reduced portion for camming a roller 329outward. At its inner end 330 the electrical plunger 321 has acylindrical bore 331 receiving a coil spring 332, which has its otherend seated on a central pin 333.

Spring 332 urges the electrical plunger outward to the position of FIG.10, and FIG. 10A.

The cylindrical bore 322 communicates with a cavity 334 by means of awindow opening 335 extending to the bore; and the cavity 334 houses amicroswitch unit 336, which is secured by a pair of screw bolts 337, andwhich has three electrical terminals 338, 339, and 340.

A leaf spring 341 is secured by screw bolts 337 to one end of the switchunit 336 in position to engage a switch button 343, but is biased awayfrom the switch button. The leaf spring 341 carries at its end aU-shaped stirrup 344 having a pivot pin 345 rotatably mounting theroller 329.

The corresponding terminals 338, 339, and 340 are shown at the switchunit 336 in the wiring diagram of FIG. 11.

The microswitch 336 is of the type having the snap button 343 normallyon open circuit at 340 and on closed circuit at 338. When the button 343is pressed inward by leaf spring 337, the switch unit 336 opens at thecontact 338 and closes at the contact 346; but when the plunger 321 isreleased by lifting the foot on the air control pedal 219, the button343 moves to the position of FIG. 11 and FIG. 10 with the circuit closedat 338 and open at 340.

The operation of the electrical plunger 321 is as follows: When the footpedal 219 is pressed, and before the air metering valve 261 is opened,the camming surface 327 engages roller 329 and moves leaf spring 341into engagement with button 343, which is pressed inward to close thecircuit at 340 and open the circuit at 338.

The roller 329 is then riding on the cylindrical surface 325 as long asthe foot pedal is pressed inward. When the foot pedal is released, theparts again move to the position of FIG. 10, opening the circuit at 340(FIG. 11).

Referring to FIGS. 12-18, these are views illustrating the air drivendental handpiece, which is driven and controlled by the foot controller.The handpiece 30 (FIG. 12) has a tubular handle '31 with an obtuse angle32 and a neck 33 supporting the contra angle head 34.

This head comprises a substantially cylindrical housing 35 tapered atits lower end at 36 and having one end 37 open to expose the shaft andthe other end closed by a threaded cap 48. Cap 48 has a central aperture50 for passing air carrying lubricant mist, which lubricates the ballbearings at this end of the housing; and the apertures 51 are for aspanner wrench.

The cap 48 is rounded at 52 to join with the head housing.

Referring to FIG. 15, this is a fragmentary bottom plan view of the head34, which is tapered down to the annular end surface 37, having acircular aperture 38 for exposing the end of the shaft 39, which has atubular bore 42 frictionally securing a plastic chuck sleeve 43 having acylindrical bore 44 for gripping the shank of a bur 112.

There is a clearance 40 between the annular end 41 of the shaft 39 andthe bore 38 which acts as an air nozzle, directing air in a conicaldirection toward the end 111 of the bur 112, this also being part of thedrive air which lubricates the lower bearings with air mist.

The neck 33 has brazed to it the nozzle conduits 144 for water and 145for chip air, each of which has its end directed to discharge water orair towardthe bur 111; and the controls are so arranged that the driveair and cooling water from the nozzle 144 are turned on at the same timeor off at the same time.

When they are off, the chip cleaning air from nozzle 145 may be turnedon by means of the foot to clean out the cavity without removing thehandpiece from the mouth.

Referring to FIG. 16, this is an elevational view of the air turbineunit 58, which is preferably removable from the head housing 35, as ithas a cylindrical shell 67, which fits in the head housing bore. Shell67 has a laterally extending lug 72 (FIG. 17) which slides in an axialgroove inside the head housing 35 and locates the inlet aperture 138 fordrive air and the outlet aperture for exhaust air in proper position toregister with the conduits 139 and 140 located in the neck 33.

The shell 67 extends inward at the bottom to engage the top of the lowerouter race 106 of the lower ball bearing assembly 61. The top of theshell 67 engages the upper flange of a stator 77, which has an annulargroove 81 registering with the air inlet conduit 139.

The upper ball bearing assembly 57 has its outer race seated in a borein the stator 77; and the top of the outer race is engaged by the cap48.

The shaft 39 carries a cylindrical rotor 105 which has a tubularextension 93 engaging the upper inner race and another tubular extension92 engaging the lower inner race, which race is seated against anannular shoulder on the frusto-conical head 65, which defines theannular conical nozzle 40.

The conical nozzle 40 is slightly enlarged at 66 at its end to increasethe amount of air discharged; and the water from the water nozzle 144 iscaused to rotate and is atomized by being sprayed into the conical airspray from the annular nozzle 40.

The upper outer race is secured to the shaft by the screw cap 102; andthe balls in the races hold the ball hearings in assembled condition andmake the turbine assembly 58 a removable unit.

The water and air conduits 144, 145 pass into the handle at the neck 33(FIG. 17) and are connected to electrical conductors so that theseconduits, which are of electrical resistance metal, may serve asheaters, if desired.

In other embodiments heaters for heating the water and the air may belocated in the control unit, which is shown in FIG. 19.

Referring to FIG. 19, this is a view in perspective of a control cabinet350, which is provided with a forked arm 351 for supporting thehandpiece 30.

FIG. 20 is a diagram showing the most important parts of the controlcabinet, which includes a water inlet 352 leading to a water filter 353.A conduit 354 extends to a water pressure regulator 355 from which aconduit 356 extends to a water solenoid valve 357, which controls awater outlet to the handpiece, also including a metering needle valve358. Thus the volume and pressure of the Water may be regulated, and thewater may be turned on or off electrically.

The air supply inlet is indicated at 359, extending to an air filter360, which has a conduit extending to an air pressure regulating valve361, the outlet of which is connected by conduit 362 to an air solenoidvalve 363, which controls the flow of air to a lubricator. A furtherconduit 364 extends to a third solenoid valve 365 having a needle valve366 for controlling chip air.

The outlet from the drive air solenoid 363 is indicated at 367; and itis connected to the lubiicator (not shown),

which provides the drive air with lubricant in the form of a mist thatlubricates the ball bearings by passing through the ball bearings aboutthe balls.

The present foot controller has its inlet 183 connected 9 to the aircompressor, and its outlet 182. connected to the air inlet 359 of thecontrol cabinet, FIG. 20.

The further details of the control unit are shown in my priorapplication, Ser. No. 798,866, filed March 12, 1959, on Control Unit forAir Driven Dental Handpieces, of which this is a continuation-in-part,the specification and drawings of which are hereby incorporated hereinby reference thereto.

Referring to the wiring diagram of FIG. 11, 368 indicates the back plateof insulation and 369 the front plate of insulation of a rotary switchindicated at 370 in FIG. 19. This rotary switch has two rotating annularcontacts 371 and 372 which are in the open position at the line contact373 and the other contact 374.

The 110 volt 6O cycle line is indicated at 375 and 376; and the latterconductor 376 extends to the common terminal 3390f the microswitch,which is adapted to control the handpiece by control of this lineconductor.

The rotary switch 370 has a left hand position indicated by the wordSpray in FIG. 11, in which fixed contact 377 is closed.

When the rotary switch is rotated to the left to the Spray position, thecircuit is conditioned to close the water solenoid 357 and the drive airsolenoid 36-3.

When the switch is turned to the right hand position, as indicated bythe word Air, the circuits are conditioned for the closing of the chipair solenoid 365; but this solenoid is also controlled by themicroswitch 336 so that the user may turn on the chip air after turningoii the drive air and water to blow air into the cavity to clean it outand to dry the cavity without removing the handpiece, and then grindingmay be resumed.

It will thus be observed that I have invented an improved control systemby means of which the user may control the speed of operation of thehandpiece from zero to maximum; and by removing his foot from the speedcontrol pedal the user may open the chip air valve, all of which isaccomplished by the foot, leaving the hands of the user free for otheroperations.

While I have illustrated a preferred embodiment of my invention, manymodifications may be made without departing from the spirit of theinvention; and I do not wish to be limited to the precise details ofconstruction set forth, but desire to avail myself of all changes withinthe scope of the appended claims.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent of the United States, is:

1. A mounting for the air valve of an air driven dental handpiece,comprising a sheet metal base plate having a circular body and aradially extending arm, said arm adapted to support a drive air valvebody provided with a pivoted bellcrank lever, said circular body beingadapted to support a round dental engine controller and having aplurality of angularly spaced radially extending sliding clamps, eachclamp comprising a sheet metal member of uniform width and thicknesshaving at its outer end an upwardly and inwardly turned clampingformation, each said member having a longitudinally extending slot inits other end, said circular body having a plurality of straps punchedout of said body sufficiently to provide a radially extending guide foreach clamping member, each guide having a threaded bore provided with athreaded bolt, said bolt being also received in the slotted end of eachclamp, said bolts having lower heads engaging each clamp on the oppositesides of each slot to se cure the clamps in fixed position on said baseplate.

2. A mounting according to claim 1, in which the upwardly and inwardlyturned clamping formations are rubber covered and the bottom of the baseplate is provided with a rubber pad of shape similar to the base plateand having a circular aperture exposing said screw bolt heads foractuation by a tool to adjust the clamps.

References Cited in the file of this patent UNITED STATES PATENTS1,182,706 Priest May 9, 1916 1,324,713 Adsit Dec. 9, 1919 1,720,389Binks July 9, 1929 1,729,802. Smith Oct. 1, 1929 2,014,642 Andrews Sept.17, 1935 2,648,234 Lester Aug. 11, 1953 2,748,229 Block May 29, 19562,855,672 FranWick et a1. Oct. 14, 1958 2,911,010 Lamburn Nov. 3, 1959OTHER REFERENCES Stephens: British Dental Journal; Volume (pages345-350; pages 347-348 relied upon) June 19, 1956. (Copy in Division55.)

